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Title: Fungicide resistance to morpholine and piperidine fungicides in barley and wheat powdery mildew, Erysiphe graminis D.C.
Author: Zziwa, Miriam C. N.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1999
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This work was carried out to study the sensitivity of barley and wheat powdery mildew (Erysiphe graminis f.sp. hordei and E. graminis f.sp. tritici respectively) to morpholine fungicides. Morpholine fungicides are classified as compounds with a low risk of resistance development. On the other hand, barley and wheat powdery mildews belong to the group of high risk fungi as far as development of fungicide resistance is concerned. Firstly, mildew isolates collected in the UK were assessed, over the period 1992 to 1995, for their sensitivity to three morpholine fungicides (tridemorph, fenpropimorph and fenpropidin). Barley isolates tended to be more sensitive to the fungicides than wheat isolates. In general, the barley mildew isolates were less sensitive to tridemorph than to fenpropimorph and fenpropidin. Cross resistance was found between fenpropimorph and fenpropidin but there was no significant correlation between barley mildew sensitivity to tridemorph and either fenpropimorph or fenpropidin. Isolates from Scotland were significantly less sensitive to fenpropimorph and fenpropidin than isolates from England. The wheat isolates tended to be more sensitive to fenpropidin than to fenpropimorph. There was no evidence of cross resistance between fenpropimorph and fenpropidin with the wheat isolates tested. A shift towards insensitivity over the period of testing was found for fenpropimorph. Wheat isolates from Scotland were found to be significantly less sensitive to fenpropidin than isolates from England. Although variation in sensitivity among mildew isolates was recorded, the results of the monitoring work confirmed the findings of field experience that morpholines are continuing to maintain an effective control over barley and wheat mildew. The variation in sensitivity appeared to be as a continuous distribution, probably related at least in part to the use of bulk isolates for most of the sampling. There, was however, no evidence of any part of the population showing a very high level of resistance.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available